PL and EL Characteristics in Bi- and Rare Earth-co-doped (La_(1-x)Ga_x)_2O_3 Phosphor Thin Films Prepared by Magnetron Sputtering

摘要

Multicolor photoluminescence (PL) and electroluminescence (EL) were observed from newly developed Bi- and rare earth (RE)-co-doped (La_(1-x)Ga_x)_2O_3 ((La_(1-x)Ga_x)_2O_3:Bi,RE) phosphor thin films. (La_(1-x)Ga_x)_2O_3:Bi,RE phosphor thin films were prepared by varying the Ga content (Ga/(La+Ga) atomic ratio) or the co-doped RE content (RE/(RE+La+Ga) atomic ratio) under co-doping Bi at a constant content (Bi/(Bi+La+Ga) atomic ratio) of 3 at.% using a combinatorial r.f. magnetron sputtering deposition method. High PL intensity was obtained in postannealed (La_(0.9)Ga_(0.1))_2O_3:Bi,RE phosphor thin films prepared with a Ga content around 10 at.%; TFEL devices fabricated using the phosphor thin films exhibited high luminance. The obtained luminance intensities in EL and PL in the phosphor thin films prepared with various contents of co-doped RE, such as Dy, Er, Eu, Tb and Tm changed considerably as the kind and content of RE were varied. Color changes from blue and blue-green to various colors in PL and EL emissions, respectively, were obtained in postannealed (La_(0.9)Ga_(0.1))_2O_3:Bi,RE phosphor thin films, i.e., films prepared by co-doping Bi at a constant content with various REs at varying levels of content. All the observed emission peaks in PL and EL from (La_(0.9)Ga_(0.1))_2O_3:Bi,RE phosphor thin films were assigned to either the broad emission originating from the transition in Bi~(3+) or the visible emission peaks originating from the transition in the co-doped trivalent RE ion.